The darkest skies I've enjoyed have been overhead in national parks. Winter nights in Yellowstone National Park so cold and so dry that stars seem almost within reach. At Natural Bridges National Monument, the Milky Way forms a horizon-to-horizon band over the landscape. Skies are so dark over most of Canyonlands National Park that shooting stars burn trails through the night.
These sorts of star shows -- and especially the Perseid meteor showers in August -- encourage you to go tentless in the parks, to sprawl on your back in your sleeping bag and doze off under the most spectacular night lights you'll ever encounter.
More and more national parks are building both delight in and respect for these dark night skies with festivals. Bryce Canyon National Park celebrates its 10th annual Astronomy Festival July 7-10, Acadia National Park is the backdrop for 2nd Annual Acadia Night Sky Festival September 9-13, and the 20th Annual Grand Canyon Star Party was held on the park's North Rim in early June. And those are just some of the opportunities that exist for you to get together with other star gazers to enjoy the night skies.
Thanks to Tyler Nordgren, though, you don't have to wait for a specific star festival to learn more about the skies over the national parks. Dr. Nordgren, an associate professor of physics at the University of Redlands in California, late this spring published Stars Above, Earth Below, A Guide to Astronomy In the National Parks.
The idea for such a book came to Dr. Nordgren during a visit to Yosemite National Park in the spring of 2005. One night he attended a campfire program that revolved around astronomy, "and what I saw that night would lead me, over the next four years, to work with park rangers from Denali in Alaska to Acadia in Maine, and Big Bend on the Rio Grande to Glacier on the Canadian border."
(Editor's note: Dr. Nordgren is scheduled to be the keynote speaker at next month's Bryce Canyon star festival.)
During that Yosemite campfire program, Dr. Nordgren met Kevin Poe, one of the National Park Service's "Dark Rangers," who happened to be visiting Yosemite from his home base at Bryce Canyon National Park. Their conversation led to a 14-month odyssey that took Dr. Nordgren to a dozen national parks to not just study the skies overhead but also to better educate both rangers and the general public on the dark skies above. Along the way he also gathered the material to write Stars Above, Earth Below.
The heft of this 444-page, $30 book can be downright intimidating, but don't let it be. Though the book's index is sprinkled with chapters touching on the Milky Way, Black Holes, and "our cosmic connection," just to cite three intriguing entries, national parks are at the heart of the book. But to enable you to better understand the skies over the parks, Dr. Nordgren lays down a thick primer of what actually is over your head, be it a star, a constellation, the Milky Way, or a comet.
East of Scorpious is the giant teapot asterism at the heart of Sagittarius. The teapot pours downwards onto the tail of Scorpius while magnificent clouds of celestial 'steam' billow between them before rising high into the sky. This 'steam' is the Milky Way and it's the reason I eagerly look for these constellations each summer. The ribbons of vapor rise northward from the teapot on the southern horizon all the way to the zenith where it forks in two and then faces away to the far northeastern horizon. If you're lucky enough to be in the southern half of the country the first puffs from the spout are the brightest part.
There are times when the text lapses almost into a college lecture:
High in the Helena Formation limestone are one billion year old fossils revealed by the retreating Grinnell Glacier. The fossils look like concentrations of giant concentric circles; what they are are stromatolites and they record some of the earliest known forms of life on Earth. A stromatolite is a large cabbage-shaped knob of limestone created by the respiration of masses of aquatic cyanobacteria (commonly called blue-green algae).
But there also are colorful first-person narratives interspersed throughout:
I saw my first glacier when I moved to Alaska as a boy at the age of 10. Portage Glacier was my 'neighborhood' glacier just an hour's ride down the Seward Highway from Anchorage. I vividly remember standing with my brother on the edge of the glacial lake as the howling, frigid wind nearly blew us into the water.
Clearly, this is not your typical national park guidebook. But then, the night skies overhead are a bit more complicated than a hiking trail or a historic building.
In pulling this richly illustrated book together -- along with his own night sky photographs the professor treats readers to some from NASA and, naturally, some from the National Park Service -- Dr. Nordgren explains how past cultures -- Chaco, Navajo, Hopi, and Chumash, among others -- viewed the night skies. He mixes the science, the history, and the skies overhead with his travels through the parks.
At Big Bend National Park, for instance, he found that "the backcountry campsites south of the Chisos Mountains have perhaps the darkest, least light polluted skies of any part in the continental United States." At Grand Teton National Park, he marvels at the Moon as the Sun's light illuminates it over the Teton Range during an eclipse back in 2007. He points to the defining feature of Crater Lake National Park when discussing the pock-marked face of the Moon.
To help you understand what you're seeing overhead, Dr. Nordgren has provided star maps that you can hold over your head.
By exploring the heavens above, he also explains some of the features of our own world, and visa versa. Yellowstone with its underlying volcanism comes into play when discussing Venus, Mars and Jupiter.
Look at a photograph of Io (one of Jupiter's moons). Every single black speck and dark circle is a hot spot like the Yellowstone hot spot; every one is a volcano. The tidal heating that produces those volcanoes long ago boiled away all the water and ice that is still found on Jupiter's other moons. What's left is a hellish wasteland of sulfur compounds in neon yellows, oranges, reds, and whites. For anyone who's ever visited one of Yellowstone's major geyser basins, this description isn't too far wrong.
There's no mistaking that this is a serious book on astronomy. Indeed, it no doubt will appear in more than a few college classrooms. But if you're looking for a sound text that explains what's overhead on your next national park trip, Stars Above, Earth Below won't fail you.